The present invention relates to a storage and mixing capsule for storing a plurality of ingredients which, in combination, form a mixture and, more particularly, to a capsule for storing such ingredients separate from one another and further providing for conveniently and efficiently mixing such ingredients into a composition.
Dental amalgams are frequently used by dentists to fill in cavities drilled in a patient""s teeth. Such amalgams typically include a combination of an alloy powder and an amount of liquid mercury. The alloy powder is typically a mix of gold or silver combined with copper, zinc, and/or tin. A temporarily pliable composition is formed immediately after these ingredients are mixed. This composition may be manipulated and formed and subsequently will harden into a solid composition. Thus, such compositions are ideal to serve as tooth fillings where a malleable substance is necessary to conform to the shape of the often irregular tooth cavity. After drilling to remove any decayed material from a tooth, a dentist will mix the ingredients of the amalgam capsule and insert the pliable amalgam into the cavity to fill the cavity. The amalgam then quickly hardens in the tooth to effectively fill the cavity and replace the removed decayed material.
Due to the above-mentioned properties of such dental amalgams, namely initially being soft and pliable but then quickly hardening to form a solid non-pliable mass, the ingredients must be stored separately until just prior to the time the dentist requires the amalgam to fill the cavity. Any premature mixing of the ingredients results in an unusable composition which hardens before it is needed and then must be discarded. Additionally, the individual ingredients may oxidize upon exposure to certain gases and air. Any oxidization of the ingredients also will result in an unusable composition which must be discarded.
Initially, in order to prevent premature mixing, the materials used to make amalgams were separately packaged. These materials were then dispensed into a mixing unit, which was then enclosed and mixing occurred by shaking. However, there were several drawbacks to these early versions of amalgam capsules, namely the oxidation of materials, along with the potential for a spill and problems with handling of the materials, particularly due to the hazardous nature of liquid mercury. As the amalgam capsules evolved, materials became pre-encapsulated with the alloy powder located in one section of the capsule and the mercury in another with a sealing mechanism included to prevent their mixture. During mixing, the seal would become disengaged or broken, thus allowing the ingredients to combine to form the dental amalgam. In these embodiments, the seal can be a foil or plastic that is pierced. Other times, the piercing can occur by the use of a separate object that becomes part of the mixing such as a free floating pestle. An example of one particular mixing capsule is disclosed in U.S. Pat. No. 3,841,467. This capsule includes a cylindrical container enclosed at its bottom end and open on its opposite end to receive an alloy. A circular plug rests on the upper edge of the container and has a central opening. A sealed plastic pouch filled with liquid mercury is placed between the upper surface of the plug and the inner top surface of the hollow cap which is in sliding engagement with the outer surface of the cylindrical container. Upon pressing the cap telescopically in an axial direction, the pouch is compressed with enough force to rupture the pouch to flow mercury through the central opening and into the container for mixing with the alloy. However, this capsule exhibits the drawback that the cap may easily be accidentally shifted or pressed downwardly to rupture the pouch and cause premature mixing of the amalgam.
Another such capsule is disclosed in U.S. Pat. No. 5,746,313 which discloses a mixing capsule including an inner storage capsule incorporating a cylindrical pestle. This pestle includes a cavity for storing a liquid component of the amalgam and has caps on both ends of the pestle. When the mixing capsule assembly is subjected to vibrational movement, the caps on the end of the pestle will impact the inner wall of the amalgam capsule thus freeing the liquid component stored therein to allow mixing with the alloy powders. Such apparatus is not free from shortcomings, however. For example, the capsule requires a relatively large number of intricate parts and is thus somewhat expensive to manufacture. Additionally, any accidental jostling of the capsule can result in premature mixing of the components.
Yet another such capsule is disclosed in U.S. Pat. No. 4,526,472. The capsule includes an outer capsule and an inner capsule, wherein the inner capsule includes a pair of open-ended cap members engaged with one another. These members form a stem and bore configuration with the stem being slidable within the bore and normally sealing the bore to trap an amalgam ingredient within the inner capsule. When the inner capsule is impacted against an interface with the outer capsule during shaking of the capsule, the stem is driven, relative to the bore, to open a passageway in order to allow the ingredient to flow into the outer capsule to mix with the ingredients stored in the outer capsule. The stem is relatively small in cross section and yet must come into direct contact with the interface of the outer capsule in order to open the passageway through the bore. Thus, in order to perform properly, the capsule requires the inner capsule follow a precise travel path during vibration. And again, these parts are manufactured at an increased cost.
As such, it will be appreciated that there is a need for a simple and efficient storage and mixing capsule to separately store the ingredients of a dental amalgam and to conveniently and reliably mix those ingredients when desired. Additionally, it would be desirable to have a capsule which incorporates a relatively small number of inexpensively-manufactured components and which is easy and efficient to assemble and use. Further, it would be desirable for such a capsule to facilitate quick and easy operation to combine such amalgam components for ease in mixing, and facilitate ease in accessing the amalgam once mixed. Further, it would be desirable to have a capsule which reduces or eliminates oxidization of amalgam ingredients. The present invention addresses these needs and eliminates the drawbacks of storage and mixing capsules of the prior art as will be described in greater detail below.
The present invention solves the problems and eliminates the drawbacks discussed above in the background of the invention. It does so by providing an efficient, inexpensive, and easy-to-use dental amalgam mixing capsule for separately storing a pair of ingredients therein and providing a structure for efficiently and reliably mixing the ingredients to form an amalgam. The amalgam capsule of the present invention includes a reliable means for storage of contents, either under vacuum or in the presence of an inert gas, to prevent oxidization. The amalgam capsule of the present invention also includes an improved structure for rupturing the seal between the cap and body of the amalgam capsule which efficiently and effectively prevents accidental premature mixing of the components.
In particular, the present invention provides a storage and mixing capsule having two components: a first receptacle and a second receptacle. The first receptacle includes an interior compartment for receiving an alloy. The first receptacle has a closed bottom end and an open top end. The open top end is further adapted to receive the lower, rupturably sealed end of the second receptacle. Finally, the first receptacle further includes a piercing element attached to a portion of the inner wall of the first receptacle and extending in a direction substantially parallel to the axis of symmetry of the first receptacle.
The second receptacle includes a closed top end and an open bottom end housing an interior compartment for receiving mercury. The open bottom end further includes a rupturable seal disposed across the open bottom end in a direction substantially perpendicular to the axis of symmetry of the second receptacle.
In a first aspect of the invention, the second receptacle further includes a conduit extending from the capsule in a direction substantially parallel to the axis of symmetry of the capsule. This conduit forms a passageway for air to move from the interior of the capsule to the exterior of the capsule so that a vacuum may be provided in the interior of the capsule to prevent the components of the amalgam from oxidizing. Alternatively, the conduit may form a passageway for a gas to move from the exterior of the capsule to the interior of the capsule. This gas is generally an inert gas which prevents oxidization of the components of the amalgam.
In use, the conduit facilitates providing a vacuum within the storage and mixing capsule by drawing air through said conduit from said interior of said capsule to said exterior of said capsule, or alternatively enables a gas to be provided in the storage and mixing capsule by forcing gas into the capsule by way of the conduit. After air has been removed and/or gas inserted, the conduit is collapsed in order to seal the interior of said capsule, thereby retaining the vacuum or gas within its interior.
In accordance with a second embodiment of the present invention, the open bottom end of the second receptacle is adapted to be received by the open top end of the first receptacle. When the second receptacle is received by the first receptacle, the two receptacles are movable relative to one another. The first receptacle further includes slots disposed substantially opposite one another proximal to the lip of the open top end of the first receptacle. Additionally, the first receptacle includes grooves which extend from the bottom of the slots around the circumference of the inner wall of the first receptacle. The second receptacle includes lugs disposed substantially opposite one another on the exterior wall of the second receptacle. These lugs are adapted to fit within the slots of the first receptacle when the first and second receptacles are engaged.
When the lugs are engaged in the slots near the lip of the first receptacle, the capsule is in a first position. The capsule can be moved to a second position by rotating the first and second receptacles relative one to another such that the lugs are slidably moved through the groove around the inner circumference of the first receptacle. When the lugs reach the end of the grooves, the capsule is in its second position. The groove on the first receptacle extends not only circumferentially around the inner wall of the first receptacle, but also is angled from the slot near the open top of the first receptacle towards the closed bottom end of the first receptacle. Thus, as the lugs are rotated through the grooves of the first receptacle from a first to a second position, the second receptacle is twisted down and into the first receptacle, thereby bringing the piercing element of the first receptacle into contact with the rupturable seal in the second receptacle. As this happens, the seal in the second receptacle is pierced allowing the liquid mercury to flow out and mix with the alloy components of the amalgam located in the first receptacle. This mixing may be enhanced by vigorously shaking the capsule. Following adequate mixing, the two receptacles are disengaged one from another and the amalgam may be removed and applied to a patient.
Thus, the present invention provides a two-piece capsule which successfully stores the ingredients of a dental amalgam separately, while allowing for their mixing when desired. Additionally, the capsule facilitates quick and easy operation for combining and mixing the amalgam components, along with ease in accessing the amalgam once formed. Also, the capsule of the present invention ameliorates the problem of oxidization of amalgam ingredients. Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate by way of example the features of the invention.